Interlocking panels and joint



Feb. 18, 15558 C. M. MOORE 2,823,826

INTERLOCKING PANELS AND JOINT 1N VENT OR Y @l-#milan BY f @s ATTORNEYSFeb, 18, 1958 c. M. MOORE INTERLOCKING PANELs AND JOINT Filed April l2,1955 7 Sheets-Sheet 2 INVENTOR @ahi/wlw@ ATTORNEYS Feb. 18, 1958 c. M.MOORE 2,823,826

INTERLOCKING PANELS AND JOINT Filed April 12, 1955 'T Sheets-Sheet 3 1NV ENTOR ATTORNEYS Feb. 18, 1958 c. M. MOORE INTERLOCKING PANELS ANDJOINT '7 Sheets-Sheet 4 Filed April 12, 1955 INVENTOR ATTORNEYS Feb. 18,1958 C. M. MOORE INTERLOCKING PANELS AND JOINT Filed April 12, i955 '7Sheets-Sheet 5 IN'VBNTOR Owns-1 MAuRlcE MooRE l BY ATTORNEYS Feb. 18,1958 I c. M. MooRE Y 2,823,826*

INTERLOCKING PANELS AND JOINT Filed April 12, 1955 7 sheets-sheet eY141A Mz, 55T* /44 Y pg# i g /9 190 ,496 7- INVENTOR CLYDE MAuRml-zMOORE ATTORNEYS Feb. 18, 1958 c. M. MOORE 2,823,826 INTERLOCKING PANELSAND JOINT V Filed April l2, 1955 7 Sheets-Sheet 7 Y lNvENTfoR" CLYDEvMAURICE Moons ATTORNEYS Unitd States ,PaffjOl i INTERLocKnsG PANELs ANDJOINT Clyde `Maurice Moore, Richmond, va.

Application April 12, 195s, serial No. 500,861

18 claims. (cazzo-16) terials, of high mechanical strength, and highlyresistant to weathering and other causes of damage.

The shipment and handling of liquid or gaseous ma`- terials is at thepresent time quite extensively practiced and presents a number ofproblems, particularly with respect to the containers employed for thematerials. The usual `type of container occupies a large v-olume ofspace when empty and necessitates considerable storage and shippingspace. 'The present invention contemplates a container or otherstructure which can be disassembled `for shipment or storage and alsocontemplates a suitable joint adaptable to containers made of materialsnot heretofore generally employedfor such purposes.

Itis necessary that a container be impervious `and inert to theparticularmaterials being handled. In presentday commercial activity, itis necessary `to handle many diverse types of liquid chemicals, many ofwhich cannot be satisfactorily handled in containers made ofconventional materials. It has been found that containers made of somethermosetting resins have-the necessary characteri's'tics to' handlemany of such chemical materials without deterioration of the containeror contamination `oit `the chemical. A well-known material, known to thetrade as Fiberglas, has been developed which consists of a body of glassfibers which may be imbedded inlthe resin to impart' Astructuralstrength to the product. glass fibers occupy substantially theentireivolume of the product and a suitable thermosetting resin'bondsthe bers together and occupiesall of the spaces therebetween and inaddition delines the outer surfaces of the product. Articles of suchmaterial can be fabricated only by mold ing processes and to moldcomplete containers of the sizes demanded in commerce and otherdesirable structures would involve extremelyilarge, `expensive and bulkyfabricating machinery. Such structures would still be subject to thevdisadvantage Vof being bulky `to handle, even when empty, even thoughthey offer substantial advantages otherwise. Among `the advantages are`lightness and toughness.

The present invention contemplates a construction of Fiberglas laminatesin the form of ypanels so shaped as to bewreadily assembled to form thedesired structure and means are provided for assemblingand joining thepanels at their -edges to provide a completely sealedjoint.

T hedisclosures made herein, while directed principally to theconstruction of Fiberglas containers, are aevertl1e- Usually, the

PatentedFelo. 18, ii

less adaptable to structures constructed of other mae terials, such asmetals, or to the construction of composite structures having portionsof metal and portions of Fiberglas sheets.

In general a container, for example, under the present inventionincludes cylindrical sidewall sections joined at their edges by means ofintertting rib-and-channel `portions. The rib portions are cut away atspaced points and thechannels are provided with projections nesting 1nthe cutaways of the .ribs and both the ribs vand projections lareprovided with aligned openings kthrough which fastenlng means extend.The fastening means not only hold the side wall panels in assembledrelationship, but extend through end panels or drum heads to hold themassembled to the side wall. The disclosure in the present case isdirected to a novel joint means that does not include sealing materialbut which provides a mechanically tight joint. In many instances it isdesirable that the container be adapted for the handling vof liquids,semi-liquids or gases, and in such cases the container may be coated onits interior surface with a layer of suitable material providing allexible impervious and inert ilm covering the entire surface and`extending across the mechanically tight joints to effect the requiredliquid seal, or, a thin `flexible bag of suitable material may be usedas a separate'liner. The invention also includes a novel arrangement ofparts Where two or more jointsintersect to effect a mechanical lockagainst `displacement and a highly eicient mechanical seal at theintersection. j

One of the objects of this invention is to provide a readily demountablecontainer construction adaptable to containers having component partsmolded of resinous material.

Another object of the invention resides in the specific novel jointstructure between adjacent panels wherein a single fastener serves tohold the entire joint in assembled and tight relationship.

l A still further object of the invention is to provide a novelconstruction at the intersection of joints between panels, suchconstruction serving to mechanicallylock the parts against lateral`displacement and to effecten etiicient mechanical seal. l

Another object of the present invention resides in the provision offastening means accessible from the exterior Aof a demountable containerand container wall structure arranged to protect the exposed portions ofthe fastening means from accidental damage.

A still further object of the invention resides in the provision ofintegral roller rings on wall panels of a container and panelconstruction arranged to nest with the roller rings upon disassembly ofthe container an'd stacking of similar panels one upon the other.

Still another object of this invention is to provide a structure ofinterlocking panels wherein the interlocking portions of the `panelscontain their own movable locking elements.

A still further object of this invention is to provide a structurecomprising interlocking panels wherein only simple tools are needed toelect assembly or disassembly of the structure.

A still further object is to provide a structure `comprising `aplurality of interlocked'panels having movable locking means and whereinjoints between different pairs of panels are serially arranged and`means for simultaneously actuating the locking means `of all thosejoints.

Still another object is to provide a structure having interlockingjoints between adjacent panels and wherein means are provided forsimultaneously actuating locking means extending along adjacent butdiiierent edges of one of the panels.

Another further object is to provide a joint structure having'self-contained locking means so designed as to escasas permit ready andfacile alignment of the locking means relative to each other in a moldfor forming the panels.

Further objects and advantages of the present invention will be apparentto those skilled in the art as the description proceeds in connectionwith the accompanying drawings, wherein:

Fig. 1 is a perspective view of an assembled container embodying thepresent invention;

Fig. 2 is a top plan view of the container shown in Fig. 1;

Fig. 3 is a partial sectional view taken substantially along the brokenline 3-3 of Fig. 2 with certain of the parts and details omitted forclarity of illustration;

Fig. 4 is an enlarged fragmentary sectional view taken. along the line4-4 of Fig. 3;

Fig. 5 is an enlarged fragmentary sectional view taken along the line 55 of Fig. 3;

Fig. 6 is a further and enlarged fragmentary sectional view taken alongthe line 6-6 of Fig. 2;

Fig. 7 is an enlarged fragmentary section taken along the line 7-7 ofFig. 2;

Fig. 8 is a perspective view of a portion of the bottom of the containerof Fig. l;

Fig. 9 is aperspective view of a portion of the top head of thecontainer shown in Fig. l;

Fig. 10 is a fragmentary radial sectional view through the structureshown in Fig. 9;

Fig. l1 is a view similar to Fig. l0 but being a section taken throughthe corresponding portion of the bottom wall `or head of the containerof Fig. l;

Fig. l2 is a perspective view of a portion of one of the panelsconstituting the side walls of the container;

Fig. 13 is an end view of the structure shown in Fig. 12;

Fig. 14 is a side elevational View of the structure of Fig. l2;

Fig. 15 is a perspective view of a portion of a panel cooperating withthe structure of Fig. 12;

Fig. 16 is a perspective view illustrating the relationship between thestructure of Figs. 12 to 14 and the structure of Fig. 9 upon partialassembly of a container;

Fig. 17 is an edge elevational view of a pair of panels showing them indisassembled condition and stacked one upon the other for storage orshipping purposes;

Fig. 18 is a sectional view taken along the line 12--12 of Fig. 17;

Fig. 19 is a detail view of an accessory for use in assembling acontainer constructed according to the present invention;

Fig. 20 is a fragmentary axial sectional view through a modified form ofjoint locking means in a container or similar structure;

Figs. 21 and 22 are transverse sectional views, on an enlarged scale,taken along the lines 21-21 and 22-22, respectively, of Fig. 20;

Fig. 23 is a detail lview of an insert and locking pin in themodification of Figs. 2O to 22;

Fig. 24 is a perspective View, parts being broken away, of a structureemploying the present invention and illustrating a novel means forsimultaneously actuating locking means along adjacent edges of onepanel;

Fig. 25 is a sectional view taken substantially along the line 25-25 ofFig. 24;

Fig. 26 is a transverse sectional view taken along the line 26-26 ofFig. 25; v

'4Fig. 27 is an exploded sectional view of a pair of panels in positionto be assembled to form a joint according to the present invention;

Fig. 28 is a sectional view of the panels of Fig. 27 showing the same inassembled and lockedrelation;

Fig. 29 is an elevational view of a mold for forming panels embodyingthe present invention;

Fig. 30 is a sectional view` through the mold of Fig.l 29 takensubstantially along the line 30f-30;l

Figs.i31,3 2 33 and 34 illustrate, respectively, fourA panels to bejoined to form intersecting joints in a structure;

Fig. shows the panels of Figs. 31 and 32 interlocked to form a firstjoint;

Fig. 36 shows the pair of panels 33 and 34 interlocked to form a secondjoint; and

Fig. 37 shows the pairs of panels of Figs. 35 and 36 interlocked to forma third continuous joint.

Referring first to Fig. l, there is shown a container in the form of acylindrical drum having a top wall or head 2, a bottom wall or head 4,and a plurality of side wall panels 6, 8 and 10. In the form illustratedthere Y are four side wall panels corresponding to panels 6, 8

and l0, each being identical to the others and each circumscribingone-fourth of the circumference of the container. The panels 6, 8 and 10are joined along adjacent edges to define axially extending joints 12and suitable fastening means to be described in detail later, extendalong the joints 12 throughout the entire extent thereof and projectoutwardly through the end walls or drum heads 2 and 4. The fastenersbear against the outer surfaces of the drum heads and hold the entirestructure assembled.

Referring now to Fig. 3, and particularly the upper right-hand portionthereof, the head 2 is of one piece construction and molded from theresinous material previously referred to. The head 2 includes anupwardly convex central web portion 14 and a thickened peripheralportion 16. Centrally of the portion 14 is a reinforcing boss 18 andradiating therefrom are radial reinforcing ribs 2t) molded integrallywith the drum head (refer also to Fig. 2). At diametrically oppositepoints the central portion 14 of the drum head 2 is thickened andprovided with imbedded inserts 22 and 24 in the form of tubular elementshaving internal threads. The imbedded inserts 22 and 24 may be providedwith suitable serrated flanges to effect a mechanical lock with thematerial of the drum head and these inserts serve as threaded openingsfor suitable bung and vent plugs 26 and 28, respectively (see Fig. l).

' Reference is now made to Fig. 6 showing an enlarged sectional view ofthe edge portion of head 2. As stated previously, the central portion 14terminates at its outer periphery in a thickened' peripheral portion 16havingv an upwardly extending flange 30 extending substantiallycompletely around the periphery of the head and having an outercylindrical surface in position to lie co-extensive 4 with the outersurface of the side panels of the container.

The thickened portion 16 also projects downwardly from the web portion14 and is configured to provide a circumferential outwardly facinggenerally V-shaped channel 32. The channel 32 is preferably lined with ametallic strip 34. The strip 34 may be rolled or otherwise formed tothedesired shape and joined at its abutting ends by welding or otherwiseand may be incorporated in 'the mold at the time the head 2 isfabricated. It will be clearly seen that the liner 34, which ispreferably of' aluminum, is permanently fixed to the head 2 since itcannot be removed from the groove or channel 32. At the lowermost edgeof the thickened portion 16 and below the channel l32 is a downwardlydirected circumfer-' ential bead 36 spaced inwardly from the outer edgeof 1 the lower wall of channel 32. The bead is of such consurface ofweb14 and an axially directed opening 40 extends through the upper surfaceof the drum head at the qui away Portion and ommunicateswiththe .cham

hel 32 as shown. In line with the opening 40 the lower wall of thechannel 32 is notched as at 42 from its` outermost edge upwardly tosubstantially the mid-portion or bottom of the V-shaped channel 32. Theedges of the notch 42 define surfaces extending in a generally radialdirection relative to the drum all as clearly shown in Fig. 9. Fig.illustrates in section the structure just described and further showsthe radial direction ofthe side edges of the notch 42.

As previously sta-ted, the panels 6, 8, 10 and the fourth panel notshown, in Fig. l are of identical construction. Each panel is arcuate inshape and defines a segment of a cylinder having axially extending edgeportions. The upper and lower arcuate edges of each panel are eachprovided with an inwardly directed ribv 44 of a shape complementary tothe transverse sectional shape of the channel 32 and are nested therein.As evident from Fig. 6, the wall thickness of the major portion of thepanels is relatively small and the lowermost wall of the V-shapedchannel 32 does not extend radially outwardly as far as does the upperwall of that channel. The difference in radial extent between the wallsof the channel is substantially equal to the thickness of the majorportion of the side wall panels so that when nesting in the assembledrelationship shown in the drawings the outer surfaces of the wall panelsare co-extensive with the outer surface of the flange 30 to define asmooth unbroken outer surface for the drum.

One of the vertical edges of each panel is provided with an inwardlyextending rib 46 (see Fig. 5) and the opposite edge of each wall panelis provided with an integral Offset portion 48 configured to form achannel 50 complementary in shape to the rib 46. When assembled as shownin Fig. 1, each edge of each panel meets with an edge of an adjacentpanel, which edge corresponds in structure to the opposite edge of thefirst panel. Preferably, the edge portion of the panel carrying the rib46 has imbedded therein a ribbonlike metallic reinforcement S2 extendingsubstantially the full length of the panel edge. If desired, thereinforcement 52 may be provided with openings to receive moldedmaterial to insure an effective bond between the parts and securelocking of the reinforcement within the panel structure. Such openingswould further insure proper flow of the resin during the moldingoperation. In like manner the edges of the panels that are provided withthe channels 50 also include imbedded ribbonlike metallic reinforcingstrips 54. Preferably and necessarily the strips 52 and 54 arepreformed, such as by rolling or the like, and placed in the mold at thetime of fabrication of the wall panels.

The ribs 46 do not have the same configuration as that shown in Fig. 5throughout their entire length but spaced portions thereof are cut awayas shown in Figs. 4, l5 and 17 at 55. Preferably, the portions cut awayas shown in Fig. 4 are of a length substantially equal to the uncutportions having the configuration of Fig. 5. The panel edges having thechannel 50 therein likewise are not of the same sectional shapethroughout their length but are provided with projections 56 (see Figs.4, 12, 13 and 16) at those locations opposite the cut away portions 55of the ribs 46 whereby to nest within those cut away portions and fillwhat would otherwise be voids in the joint. Reference to Figs. 3 and 7shows the internested relationship of the structure described as viewedin section along the joint.

The projections S6 in channels 50 are provided with longitudinallyextending tubular metallic inserts 58 delining openings extendinglongitudinally of the joint. The inserts 58 are welded as at 59 orotherwise secured to the reinforcing members 54 to be maintained spacedtherefrom and to effect a lock between the insert 58 and the edgeportion of the corresponding panel. The portions of the rib 46 that areof fullsection, asshown in Eig. `.f1/are also vprovided withlongitudinally `extending tubular metallic inserts 60 the-rib and weldedor otherwise secured to the reinforce0 ment members`52. As evident fromFig. 7` of the drawings, the tubular inserts 58 and 60 are axiallyValigned when the panels are in the assembled relationship shown anddefine a continuous opening extending the full length of the joint 12. t

The bottom wall or head 4 (see also Figs. 8 and l1) is generally similarto the head 2, identical parts bearing the same reference numerals, butthe flange 30 on the bottom head 4 is not cut away in the same manner ashead 2 is but is provided with the miter notch 42 at the opposite orlower end of each joint: 12. An opening 62 opposite the notch 42 is inaxial alignment with the opening 40 in the head 2. The opening 62extends through the head 4 and part of flange 30, thus 'defining achannel 64 at the inner side of flange 30. Adjacent the channel 64 andon the outer surface 'of the web 14 of head 4 integrally moldedprojections 66 are provided on opposite sides of the channel V64.

With the parts assembled as shown in Figs. 3 and 7 an elongated fastener68 is passed through vthe aligned openings in the panels and heads tohold. the entire assembly in assembled relationship.` The rod 68 is bentat its lower end to provide a short lateral portion 70 lying between theprojections 66 on head 4 and bearing against the lower surface of web14. The shank or body portion of the rod 68 extends through and occupiesthe openings dened by inserts 58 and 60 and extends upwardly through theopening 40 in head 2, its upper end being substantially flushwith theouter surface of the head 2. The upperiend of the rod 68 is furtheraxially bored and internally threaded as at 72 and receives a bolt 74having a head 76 and washer 78 bearing against the outer surface of theupper drum head 2. It will be obvious that the rod 68 must be insertedfrom the bottom of the container after the parts have been assembled andthereafter the cap screw 74 engaged and drawn tight to place the rod 68under tension and maintain the container in assembled relationship.

To facilitate insertion of the rods 68 in the aligned openings of theheads and panels, an accessory 80 (Fig. 19) is provided. The accessory80 consists of a tapered plug having a threaded shank 82 receivable inthe thread-l ed bore 72 of rod 68. The diameter ofthe base of taperedplug 80 is equal to the diameter of the rod 68 and the accessory has arounded blunt end readily inf sertable through the openings even thoughthey are not exactly aligned at that time and the tapered sides thereofwill effect a wedging action to draw the openings into alignment forreception of the rod 68. After the rod V68 has been threaded through theopenings, the accessory 80 may be removed and the bolt 74 applied asdescribed# If desired, the accessory 80 may be kept with the parts lofthe container at all times such as by providing a clip or holdertherefor on the bung 26 or at any other convenient location on thecontainer.

The joints 12 between the side panels of the container extend to thejoints between the upper edges of the panels `and the upper drum head 2and also to the joints between those panels and the lower head 4.Provision is made for locking the side panels to the drum headsindependently of the rods 68 to relieve those rods of all shear stressesdue to any tendency of the panels to shift circumferentially relative tothe heads. As previously described, the drum head 2 is provided withnotches 42 and Figs. 12 to 14 illustrate the construction of the upperportions of the side panels at the edges; thereof forming the channels50. As clearly shown in the drawings, the channels 50 are extended andmitered at their ends, as at 84 to a shape exactly complementary to thenotches 42 and it will be evident that themitered ends`84 arepositionable within the notches 42 in snug nested relationship thereto.The small curved portions `85 engage the imbedded inthe material of befurther described in detail.

outer surface ofvbead 36 of the head to effect further reinforcement butmay be omitted if desired by continuing the flat edge surfaces of miter84 to the extreme outer edge of the channel structure. The ribs 44extending along the upper edges of the side panels terminate at theinner face of the channels 50 and are provided with inclined endsurfaces 86 co-extensive with the corresponding inner side face ofthechannel 50. Fig.v 16 illustrates the portion of the side panels shown inFigs. 12 to 14 when assembled with the structure illustrated in Fig. 9and it will be seen that the assembly provides a positive lockragainstlateral shifting of the panel 8 circumferentially about the head 2. Fig.16 also illustrates the fact that the opening 40 through head 2 is inaxial alignment with the opening through insert 58 in'projection 56 ofchannel 50. The rod 68 will ultimately pass through these openings. Itis also clear from Fig. 16 that the channel 50 lis complemented by theend face 86 and cooperates with the channel 32 of head 2 to form arightangle channel Iadapted to snugly receive the upper corner portionof an adjacent side wall panel 10. Fig. illustrates they portion of thepanel 10 receivable in the channels shown in Fig. 16. The panel 10 isprovided with the upper lrib 44 previously described which is formedintegral with the panel and integral with the end portion of the rib 46extending along joint 12. Fig. 15 clearly shows the cutaway portion 55of the rib 46, described in connection with Figs. 4 and 5, and clearlyillustrates how the projections 56 of channels 50 may nest therein tobring the inserts 58 and 60 into axial alignment. The lower corners ofthe side Wall panels and corresponding portions of the lower head 4 `areformed exactly as described in connection with Figs. 12 to 16 and neednot While the description has referred to panels 8 and 10 as beingseparate and apparently different panels, they are in fact identical.One upper corner of each panel is constructed as illustrated in Figs. l2to 14 while the opposite upper corner thereof is constructed as shown inFig. 15, thus the panels are interchangeable.

Referring again to Fig. 1 and Figs. 17 and 18, it will be noted that theside wall panels are provided with integral circumferentially extendingribs 88 on their outer surfaces. The ribs 88 on each panel definesegments of roller rings and are so formed and shaped that thecornpletely assembled container includes continuous rings around itsperiphery adapted to support the drum for rolling contact with a surfacewhen lying on its side and also effecting substantial reinforcement ofthe relatively thin side wall panels. Each of the roller ring segments88 extends to the edge of its panel and is so formed at its ends as topresent surfaces co-extensive with the inner face of channel 50 at oneend and with the outer face of rib 46 at the other end (see Figs. 4 and18). When the parts are assembled to a complete container, the ends ofthe ring segments 88 are brought into abutment as shown in Fig. 4 todefine a continuous ring around the periphery of the drum. When thepanels and heads of the demountable drum of the present invention aredisassembled they may be nested or stacked in a manner'to occupy aminimum of space to facilitate storage ori-shipment thereof. The mannerof nesting the heads 2 Iand 4to each other has been previously describedand itiwill be obvious that the side wall panels may be nested sincethey areof lsegmental-cylindrical shape. The presence of the roller ringsegments 88 on the side wall panels and the 'fact that the ribs 46project inwardly of the inner face of the panels even `at thoselocations Where the ribs are cut away, would prevent the panels fromlying close to the outer peripheries of the rings 88. 'From the drawingsit is apparent that the ring segments 88 extend to the edge portions ofthe panels adjacent rib 46 at locations `where .those ribs. are cut awayto receive the projections 56 of a mating panel. Portions of ribs 46even at those cut away locations extend inwardly of the inner surface ofthe panelwall and those inwardly projecting portions are cut away as at(Fig. 17) to define circumferential notches complementary in shape tothe outer edges of the roller rings 88. Thus, side panels may be nestedand stacked in the manner shown in Figs. 17' and 18 with end portions ofroller rings 88 on the lowermost panel received within the notches 90 topermit the lowermost ring segment 88 to contact the inner surface of theupper panel 10 throughout the entire arc of the panel. It has been foundthat the provision of the notches 90 will permit a substantially greaternumber of panels to be-stacked in Ia given space than would otherwise bepossible.

For purposes of storage and/or shipment, the rods 68 may be inserted inthe lopenings at either edge of a panel and the cap screws temporarilyreplaced to prevent loss of the fastener rods during handling, shipmentor storage.

The structure thus far described provides a demountlable containerhaving snugly intertting portions defining joints and is perfectlysatisfactory for the handling of a great variety of materials.

The illustrated embodiment includes four `side wall panels, eachextending throughout 90 of the periphery of the drum. Since thecomponents of the drum are of molded resinous material, it is necessarythat all portions thereof be so `angularly related that they may bereadily removed from the forming mold. Referring again to Figs. 4 and 5,the tapered side faces of the ribs 46 and the channels 50 must be soangularly positioned that the molded panels may be readily removed fromthe mold. Since each panel lis provided with a rib 46 at one edge and 4achannel 48 at the other and since each panel denes a 90 arc, it is clearthat the included angle, identified Vby A in Fig. 5, must not be lessthan 90. If that angle is exactly 90, the inner face of the rib will beexactly parallel to the inner surface of the channel at the oppositeedge and some difficulty will be experienced in stripping the moldedpanel from its forming mold. Preferably, the angle A is slightly greaterthan 90, an angle of 92 has been found satisfactory. With the ribs andcomplementary channels formed to an included angle of 92, it will beevident that the parts interiit with a wedging action to firmly hold theabutting surfaces together and effect an efcient mechanical joining ofthe panels .along a relatively tight joint.

The mechanically tight joint thus far described would not provide asufficiently tight container for the handling of many liquid productsand particularly petroleum products of low specific gravity. To adaptthe present demountable container for handling of such liquid materials,it is necessary that sealing means be provided to hermetically seal theentire container and particularly at the joints thereof. A satisfactorymanner of providing such a seal resides in providing the entire innersurface of the assembled container with a lm or layer 92 (see Figs. 4, 5and 6) of a suitable sealing material of suicient flexibility towithstand the flexures to which the panels may be subjected and adheringto the walls of the container. The film or layer may be applied inliquid forni to spread a film over the entire inner surface of the drumand allowed to set or harden to a solid state. Modications of materialspresently available on the market and sold under the trade names Primoidand ,Corosite have proven satisfactory for this purpose in manyinstances. It will be apparent that the material of the film or layer 92must be inert to the particular material being handled and may beapplied in the form of an emulsion or solution of a suitable rubber orsynthetic rubberlike material or may, in some instances, consist of adispersion or solution of silicone resin. Such a film may besatisfactorily applied by introducing into the vassembletieontainer aquantity of the liquid material in excess of that necessary to providethe film and by manipulating the container `to cause the liquid to flowover all surface portions `of the inside and then draining the excessoff. After the film has set, the container is ready for use, A containerso sealed may be readily disassembled in the obvious manner which would,of course, result in tearing the film 92 at the joints. The :film maythen be stripped from the inner surface of the panels or may be removedby suitable solvent or heat treating processes; Upon reassembly of theparts a new film will then be provided in the manner described.

During the dispersion of the liquid over the surface of the drum toprovide the seal, in the manner described above, it may be advantageousto seal the drum and introduce compressed air or the like to maintain apressure therein somewhat greater than atmospheric pressure to insureentry of the film forming material into small crevices 'and cracks atthe joints to more effectively seal the joints against leakage of liquidmaterials. A pressure of about 7 pounds per square inch aboveatmospheric pressurehas been found satisfactoryfor this purpose.

As previously indicated, the material of the panels and drum headspreferably consists of a reinforced thermosetting resin material. Asatisfactory structure comprises a mat `core of fibrous glass betweeninnerand outer layers of plastic-impregnated glass cloth. Preferably thelayers of cloth lie closely adjacent the outer surfaces of the panels toconfine Vthe mat core during the molding process and `t`o impart greatstructural strength to the panels. Suitable fibrous glass mat and glasscloth are obtainable under the trade name of Fiberglas At the portionsof the panel where the sections are thickened, such as at the edgesdefining the channels and ribs for the joints, the roller rings, theflanges on the drum heads, etc., extra filling material of glass fibermat r cloth is provided since those portions of the structure aresubjected to excessive impact loads and must be constructed sufficientlystrong to withstand those impacts. Although it is preferred to useFiberglas reinforcement, clearly other materials may be employed as afiller or reinforcing medium for the panels. 1 At certain locations inthe panel construction it has been found necessary to employ additionallayers of impregnated glass cloth. Reference to Fig. 4 indicates thatthe top or outer surface of the `metal insert 58 lies very close to theouter surface of the projection 56. At this point, Vand any othersimilar locations in the structure, it is preferred `that several layersof glass cloth lie over the insert 58 and extend downwardly into thebody of the projection to satisfactorily lock the projection to thepanel edge. It `will be realized that considerable lateral force existstending to pull the insert 58 outwardly of the channel when thecontainer is assembled and the extra layers of `glass cloth provide a`suitable joint between the insert and the body of the material. At theportions h-avingisuch thin sections as that just described, no fibrousrnat is employed between the layers of glass cloth. y

While it is contemplated that any suitable thermosetting resin may beemployed, it is preferred that the container be constructed of apolyester resin. A satisfactory resin is available on the market underthe trade name of Laminac, distributed by the American CyanarnidCompany. Preferably, the resin is impregnated with a suitable metallicpigment or powder, such as the aluminum powder pigments with which manyresins are commonly impregnated at present. Such a pigment in thematerial imparts to the product a constant desirably uniform appearance.The Laminac resin referred to is of the low pressure type from whichproducts may be molded by processes involving very low mold pres- Sores.y l Y During the molding 'operation ofthe side panels the te'- inforcingstrips 52 or 5.4 with their associated tubular' inserts are positionedwithinthe mold and it will be clear that the shape of the moldcorresponds to the contour of the panel structure intended to cooperatewith the particular one being considered. Those parts of the moldcorresponding to theprojections 56 will abut against the ends of theinserts 60 and thereby plug thelopen ends thereof to prevent entry-ofplastic material therein during the molding operation. If desired,separate plugs may be insertediin theiinserts and such plugs may consistof suitable core material removable `by heat or solvents. Preferably thefastenersy 68 and bolts 76, along with the bung `and vent plugs 26, areof corrosion-resistant metal orso treated as `to be resistant to thematerials being handled-and (weather. It has 'been found that a thinplating of cadmium on steel members provides a satisfactory protectivecoating.

The container herein 'described and hereinafter claimed is for use underconditions where no satisfactory demountable container `has heretoforebeen available. For instance,- in shipping foodproducts and in handlingmilitary supplies such asigasoline, oil, napalm, etc., the presentinvention proves highly valuable since it may be easily assembled or`disassembled `in the field, without specialized tools or equipment, andsince it occupies so little space when disassembled.A

Referring now to Figs. 20 through 23, the joint of this modification isshown embodied in a container or similar structure having end walls 102and r104 `and a plurality of side panels including panels 106 and 108.In general, `the shape `of the panels of this modification are the sameas those described 'in connection with Figs. l through 7. Adjacent edgesof the `side panels 106 and 108 areV provided with overlapping portions,one of which defines a channel 110 ,(see Figs. 2l and 22) -and the otherof which provided with aligned but axially spacedribl portions 112. Likethe previous embodiment, projections 114 are located in the channel 110in position to occupy and `fill the `spaces between the aligned ribs`112. Each of the ribs and `projections `is providedwith a longi tudinalopening therethrough in `which a locking `insert 116 (see also Fig; 23)lis embedded. The openings defined by the inserts 116 define acontinuous closed passageway extending the length ofthe joint betweenthe panels 106 and 108.

The inserts 116 are Iall identical in `construction and, asshown,-comprise metal tubes 118and 1-20 telescopically fixed in oppositeend portions of a slightly larger metal tube 122. The opposed ends 124and 126 of the tubes 118 and 120, respectively, are spaced apart `anddefine, with the inner surfaceio-f tube L122, aniannular chamber 128between the ends of the insert 116. A locking `pin 130 is slidablypositioned in theiinsert 116 and its length is substantially exactlyequal to the overall length of the insert. Preferably, one end of thepin 130 is rounded, as `at 132, whereas its `other end is left fiat. Ifdesired, the insertij116 could be a single: integral tubular elementenlarged y.intermediate `its ends to provide the chamber 128 andshoulders 124 and 126.

The pin 130 -is .provided intermediate its `ends with a circumferentialgro-ove 134 in which a split ring 136 'is positioned. The `groove134isipreferably of such `radial depth that the split ring 136 may Aberadially contracted to lie completely within the outer `periphery of thepin 130; Byithisconstruction, the `tubes 118, 120 and 122 may be`assembled and permanently fixed together and thereafter the pin 130 maybe `inserted into one end of the insert 116 and ring 136 -may Abecontracted to pass through either tube 118 or 120. When the pinhas-.been inserted to a position where the ring 136 is within the`:hamber 128, the ring expands tothe position shown in the drawings andlocks the `pin 130 in the insert. The parts are so proportioned andpositioned that when ring 136 abuts the end face 126 oftube 12.0, thepin ,130 is entirely and completely contained within the Vinsert 1'16with its ends in Asubstantially flush relation Withthe i'co's assenzeresponding ends of the insert and the ring 136 frictionally holds thepin 130 in that position by virtue of its tendency to, expand radially.When the pin 130 slides axially through the insert 116 to a positionWhere ring 136 abuts lend face 124 of tube 118, the rounded end of thepin projects a substantial distance from the corresponding end of theinsert.

Although inserts 116, pins 130, and rings 136 have been described asmetal, they are not necessarily so. They may be of any other suitablematerial where it is desired Ato exclude all metal from the structure.

As previously described, the ribs on panel 108 and projections inchannel 110 are each provided with an insert of the type described inconnection with Fig. 23 and all the inserts are in axial alignment whenthe panels are in assembled relationship.

As shown in Fig. 20, the upper and lower ends of the joint are delinedin part by passageways 138 in panel 108 outwardly of the last insert.Each of the passageways 138 is provided with a member 140 threadedtherein for axial movement along the passageway. The end walls 102 and104 are provided with passageways or openings 142 in alignment with thepassageway of the joint and through which a suitable wrench or tool maybe inserted to engage and actuate either of the threaded members 140 formovement in either direction along the joint passageway. Fig. 20 showsthe joint with the panels locked together 'to form the desiredstructure. In this condition a suitable tool may be inserted in thelower opening 142 and 'the lowermost member 140 may be rotated to threaditself downwardly in the passageway 138 and thereafter the upperthreaded member 140 may be threaded downwardly and thereby push all thepins 130 downwardly until each is completely contained within itscorresponding insert 116. When that condition is reached, the splitrings 136 engage the surfaces 126 and stop the pins 130 with their endsflush with the ends of their corresponding insert 116. In this positionthe panels are not locked and panels 106 and 108 may be readilyseparated laterally, as shown in Fig. 27.

To assemble a structure embodying this joint, the ends of pins 130 mustbe in tiush relation with their inserts 116 and releasably held thereagainst accidental displacement, the panels are then positioned to nesttheir respective ribs and projections with each other, and the lowermostthreaded member 140 may then be screwed upwardly to slide the entire rowof pins upwardly so that each projects from its own insert and partiallyinto the insert thereabove to positively lock the panels together andthereby lock the structure in assembled relation.

Referring now to Figs. 24, 25 and 26, the structure shown therein may beof generally cubical shape and may be a container or any other desiredstructure. In this vform of the invention side panels 144 and 146varejoined together along a joint 148 but in angular relationship to eachother whereby a corner of the structure is formed. Transverse edges ofthe panels 144 and 146 are jointed to an end panel 150 to form a 3-panelcorner of the structure.

The joints employed with this modification are essentially the same asthat described in connection with Fig. 20, the channel of the end panel150 being formed by anges 152 and 154 having spaced projections (notshown) integrally formed therein. The overlying edge portions 158 of thepanels 144 and 146 are provided with spaced aligned rib sections 156adapted to fit and nest between spaced projections of panel 150. Each ofthe rib sections of the side panels and the projections in the channelsof the end panel are provided with inserts which may be identical tothat shown and described in connection with Fig. 23. In thismodication,an end pin 160 (see Fig. 25) on the panel 144 is fixed to a flexiblecompression member 162 and the latter extends around the corner of thepanel 144 and is fastened at its other end to an end pin 163 on theadjacent edge of the panel 144. In this construction the inserts 116in-those projections 114 nearest the corner of the panel 144 are ofsomewhat different construction than that shown in Fig. 23. In this casethe inserts 116 on adja- 'cent edges of the panel 144 constitute asingle member extending around the corner of the panel and including aportion 164 of reduced diameter, through which the flexible compressionmember 162 extends loosely. As will be obvious from Fig. 25, pins at theupper edge of panel 144 are moved to the left, the end pin 160 pushedahead of them and, through flexible compression member 162, the end pin163 will be pushed downwardly and that, in turn, will push the row ofvertical pins 130 downwardly, when it is desired to actuate the lockingmeans. Thus, by manipulating a single element at one corner of the panel144, all the pins on at least two edges of that panel may be actuated ineither direction to lock or unlock the structure. Clearly, the structurehere described could be employed to simultaneously actuate all of thelocking pins on any selected number of adjacent edges of a panel.

Figs. 27 and 28 illustrate a modified form of means for actuating thelocking pins previously described. The interlocking joint of the presentinvention is readily adaptable for locking together the panels ofstructures other than containers. Figs. 27 and 28 illustrate, in a broadway, a pair of panels adapted to be locked together and employed in anydesired structure. The panels and 172 are provided with overlapping edgeportions, one of which defines a channel 174 having spaced projections176 therein and the other of which is provided with spaced but alignedrib sections 178 and 178vcornplementary to the channels 174. Each of therib sections 178 and projections 176 has an insert 116 cmbedded thereinand its associated pin 130 slidable therethrough. As is clearly evidentfrom Fig. 27, when the pins 130 are wholly contained within the insertand with their ends flush with the ends of the insert, the panels may bereadily separated or assembled by sim-ple lateral movement of the ribsections 178 outwardly of the channels 174. The condition illustrated inFig. 27 obtains also in the modifications of Figs. 20 and 24 under thedescribed conditions. When the panels 170 and 172 of Fig. 27 are movedinto interlocking nested relationship, they assume the relativepositions shown in Fig. 28. The rib section 178 of panel 170 need not beprovided with an insert 116 but may have merely a bore or passageway 180therethrough in alignment with the openings through the inserts 116. Apin 182 is slidably positioned in the passage 180 and is of such lengththat when its inner end is flush with the inner end of the rib 178' (asshown in Fig. 27) its outer end projects a substantial distance beyondthe end of the joint and a transverse edge 183 of the panel 170. Whenthe panels have been rnoved to the interlocking relation shown in Fig.28, the end pin 182 may be pushed or driven inwardly to the left, to theposition shown in Fig. 28, and will thereupon drive the entire row ofpins 130 ahead of it into. position to lock the panels in assembledrelationship. It is contemplated that the other end (not shown) of ajoint as shown in Fig. 28 be also provided with a passagewaycorresponding to the passageway 180. Preferably, however, no pin islocated in that passageway. When it is desired to disassemble thepanels, any suitable tool may be inserted in the passageway at the otherend of the joint and thereby the entire row of pins 130 may be moved tothe right to assume the position, relative to their correspondinginserts 116, as shown in Fig. 27, whereas the panels may be readilyseparated.

Figs. 29 and 30 illustrate a mold suitable for the production of panelsincorporating the present invention.` The mold preferably comprises alower body portion 184 and an upper portion or cover 186. The moldportions 184 and 186 are provided with suitable cavities defining achamber 188 of'the exact shape and dimensions of the outer surfacesrofthe panel to be molded. The lower portion 184 may be provided withrecesses 190 in which the ribs or projections of the panel are formed.The portions 19,2 of themold correspond in size and shape to ethe ribsor projections to mate with the rib or projecltion formed in the cavity190. The extensions 192 are provided with aligned openings 194 in whichpins 196 are slidable. The outermost edge portions of the mold areprovided with passageways aligned `with the passageways 194 and in whichdrive pins 198 are mounted. Each of the drive pins 198 may be providedwith a head 200 and which is of such length that the head 200 is at alltimes outside the outer surface of the mold. Preparatory to molding apanel in the mold shown, inserts 116 are positioned in the cavities 190with their pins 130 in the relative position shown in Fig. 23. With theinserts 116 thus positioned in the cavities 190, the end pin 198 may bedriven inwardly to project the pins 130 into interlocking `relation withthe passageways 194 and at the same time project pins 196 intointerlocking relation with the aligned end of an adjacent insert 116.Thereafter, the cover or top portion 186 is placed on the mold body 184,clamped or held thereon by any suitable means, and a panel molded in themold chamber 188. By the means shown and described, all inserts 116 areimbedded in the material of the panel and are positively positioned incorrect axial alignment with each other.

After the panel is molded and cured, the pin 198 at the right side ofFig. may be driven to the left to unlock the molded panel from the moldand permit its ready removal. y l

Referring now to Figs. 31 through 37, Figs. 31 through 34 show panels202, 204, 206 and 208.` It is contemplated that t'he four panels .bejoined to form a 4-panel subassembly constituting a part of a largerstructure. It is further contemplated that the edge portions of panels202 and 208 shown in Figs. 3l and 34, and the portions of panels 204 and206 shown in Figs. 32 and 33, respectively, illustrate diagonallyopposite corners of identical panels. In other words, the four panelsshown in these figures are of identical construction, the lower righthand corner being as shown in Fig. 31, the lower left hand corner beingas shown in Fig. 32, the upper right hand corner being illustrated inFig. 33 and the upper left hand corner being as illustrated in Fig. 34.In this form the right hand edge of each panel is provided with spacedaligned ribs 210 and the left hand edge of each panel is provided with acontinuous channel 212 complementary to the ribs 210 and havingprojections 211 therein. The ribs and projections may be provided withthe inserts and pins previously described. The uppermost edge of eachpanel is provided with a continuous channel 214 in which spacedprojections 216 are molded, corresponding to the projections in thechannels in the previous embodiments. The'lowermost edge of each panelis provided with spaced aligned rib portions 218. The projections 216and the rib portions 218 may also each be provided with the inserts andpins referred to and which are in alignment when the panels are inassembled relation, as described in connection with the previousmodifications.

It will be clear that the panels 202 and 204 may be assembled by placingribs 210 in channel 212 and the associated pins moved to lockingposition. Panel 206 may be assembled to panel 208 in the same manner toroduce the interlocked pairs of panels illustrated in Figs. and 36. lnthis condition of assembly, the channels 214 along the upper edges ofthe panels 206 and 208 extend continuously across the joint betweenthose panels except for the notch 220 extending downwardly to about thecenter of the channels 214. The channel 212 on panel 204 is providedwith a pointed lowermost end complementary to the notch 220 and the ribportion 218 on panel 14 204 constitutes an exten-sion of the endmost ribportion 218 of panel 202. As illustrated in Fig.,35, each of the ribsections 218 is provided with a slidable pin 222 in its longitudinalopening andthe projections 216 of Fig.v 36 are also each provided with apin 224 in their longitudinal openings.

The pair of panels shown in Fig. 36 may then be placed with their upperedges `in overlying relation to the lower edges of the pair of panelssh'own in Fig. 35 with the rib portions 218 nesting betweentheprojections 216, all as shown in Fig. 37. Thereupon an end pin (notshown) on one of the panels may be pushed inwardly to thereby move allthe pins 222 and 224 into interlocking relation with the passageways onan adjacent `panel and thereby lock the four panels in theassembledrelationship shown. By this means, applicant has provided a panelstructure capable of assembly in any required or desired numbers to forma multitude of different structures.

The assembled panels 206 and 208 of Fig. 36 could be a single panelhaving the notch 220 therein for mating with the panels of Fig. 35 toform a T-joint. It is to be noted that the edge surface 230 of the notch220 is parallel to the outer surface of channel 212 (Fig. 35) which itabuts when the structure is complete, without any voids between theparts.

If desired, the passageway along the joint, the inserts 116, and/ orpins may be omitted and the panels held in assembled relation by othermeans, such as by a tension band or strap surrounding the entirestructure.

While a limited number of embodiments of the invention have been shownand described herein, it is to be understood that many modifications andequivalents may be resorted to without departing from the scope of theinvention as defined in the appended claims.

I claim:

1. A demountable container comprising, adjacentwall panels havingoverlapping edge portions defining a joint, said overlapping portionsbeing further provided with alternating projections along said joint andextending transversely thereto but between said overlapping portions andconcealed therebetween, the opposed outer surfaces of said overlappingportions being continuous and uninterrupted, said overlapping portionsof each panel further having continuous free edges engaging the otherpanel adjacent the iuncturebetween said other panel and its overlappingportion, said projections being provided with aligned openings defininga continuous peripherally closed passageway extending along said joint,and rigid fastener means extending along said joint and through saidaligned openings to hold said panels in assembled relationship.

2. A container as defined in claim 1 including end panels arrangedtransverse to said wall panels and extending across said joint, said endpanels having edge portions interlocking with adjacentedges of said wallpanels at interfaces extending generally transverse to said wall panels,said fastener means comprising an elongated rigid fastener having endportions extending through said end panels, and means carried by saidfastener bearing against the outer face of each of said end panels.

3. A demountable container comprising, adjacent wall panels havingoverlapping edge portions defining a joint, one of said edge portionsbeing provided with a continuous channel extending along said joint andfacing said other edge portion, the other of said edge portions having arib complementary to Said channel and nested therein; longitudinallyspaced portions of said rib being cut away; said channel havingprojections therein, said projections being complementary to and nested`in said cut away portions, the opposed outer surfaces of saidoverlapping edge portions being continuous and uninterrupted, said riband said projections being provided with aligned openings extendingalong said joint, and rigid fastener means extending through saidaligned openings to hold said lwall panels in assembled relationship,said overlapping portions of each panel further having continuous edgesengaging the other panel adjacent the juncture between said other paneland its overlapping portion.

4. A demountable container comprising, adjacent wall panels ofreinforced resin material having overlapping edge portions defining ajoint, one of said edge portions having a V-shaped channel integraltherewith and extending along said joint and facing said other edgeportion, an elongated metallic reinforcing member of V-shape, transversesection imbedded within the material of said channel walls, the other ofsaid edge portions having an integral rib complementary' to said channeland nested therein, a ribbonlike metal reinforcing member imbedded insaid other edge portion adjacent the base of said rib, longitudinallyspaced portions of said rib being cut away, said channel havingprojections therein complementary to and nested within said cut awayportions, said rib and said projections being provided with alignedopenings extend ing along said joint, tubular metallic liners in saidopenings, each of said liners being secured to the imbedded reinforcingmember of the corresponding edge portion, and 'an elongated fastenerextending through said aligned openings to hold said adjacent panels inassembled relationship.

5. A demountable container comprising an end panel having a firstchannel along one edge thereof, one side of said channel having a notchextending substantially to the mid portion of the channel, a pair ofadjacent wall panels having edge portions extending transversely of saidchannel at said notch, the edge portion of one adjacent panel defining asecond channel formed at one end complementary to said notch and nestedtherein to define intersecting channels forming a T at said notch; thepanel having said second channel having a rib projecting from anadjacent edge and nested in said first channel on one side of saidnotch, the other of said adjacent panels having a rib on its said edgeportion nested in said second channel and a rib on its adjacent edgenested in said first channel on the other side of said notch, and a-fastener extending through said end panel and notch and engaging eachof said adjacent panels.

6. A container as defined in claim wherein the'ribs 0n said adjacentpanels nested in said first channel extend into end abutment with`eachother Ialong a surface co extensive with one side of said secondchannel.

7. A structure comprising, a pair of adjacent panels having overlappingedge portions defining a joint; an edge portion of one of said panelscomprising a continuous channel extending along said joint and facingsaid other edge portion; the edge portion of the other panel havinglongitudinallyspaced but aligned ribs complementary to said channel andnested therein; said `channel having projections therein complementaryto and nested in the spaces between said ribs; said projections and ribshaving aligned openings extending longitudinally therethrough anddefining a continuous closed passageway along said joint; a locking pinslidable in each of said openings, each locking pin being of the samelength as its corresponding opening whereby it may be completelycontained therein; and means on one of said panels, at one end of saidjoint, for moving an adjacent pin longitudinally of said passageway inone direction to `push all said pins from an end of their respectiveopenings and partially into the next adjacent opening to thereby locksaid panels together.

8. A structure as defined in claim 7 including further means on one ofsaidpanels at the other end of said joint for moving said pins in theVother direction.

9. A structure as Vdefined in claim 7 wherein said lastnamed meanscomprises a screw member threaded in an end portion of said passageway.

10. A structure as defined in claim 7 wherein said lastnamed meanscomprises an end pin slidable in said passageway and projectingoutwardly from the end thereof.

1l. A structure Vas defined in claim 7 wherein said panels are formed ofreinforced resinous material and wherein each of said openings isdefined by a metal tube imbedded in said material.

12. A structure as defined in claim 7 including a second pair of similarpanels arranged with the defined joints of each pair positioned in axialalignment, the end pin in one joint abutting the adjacent end pin of theother joint, saidpairs of panels having edge portions defining a furtherjoint extending to and transversely of said defined joints.

13. A structure as defined in claim 7 including limiting means in eachopening for limiting axial movement of the pin therein between thepositions where the pin is entirely within the opening and where itprojects partly from one end thereof.

14. A structure as defined in claim 13 wherein said limiting meanscomprises, one annular chamber around each pin between the ends of itsassociated opening, an annular groove around each pin, and a split ringin each groove engageable with the ends of its associated chamber.

l5. A structure as defined in claim 7 wherein one of said panels isformed with another edge portion angularly related to but adjacent saidfirst edge portion; said other edge portion being provided with asimilar means, including locking pins; and means connecting the end pinof said one edge portion with the adjacent end pin of said other edgeportion to cause the pins of both said edge portions to movesimultaneously.

16. A structure as defined in claim 15 wherein the adjacent endopeningsin -said one and another edge portions are defined by a singletubular member having a curved portion between said edge portions, and aliexible compression member joining the pins in said tubular member andextending through said curved portion.

17. A structure comprising, a first panel having a first channel alongone edge thereof, one side of said channel having a notch extendingsubstantially to the mid portion of the channel, a pair of adjacent wallpanels having edge portions extending transversely of said channel atsaid notch, the edge portion of one adjacent panel defining a secondchannel formed at one end complementary to said notch and Vnestedtherein to define intersecting channels at said notch without voidstherebetween; the panel having said second channel also having a ribprojecting from an adjacent edge and nested in said first channel on oneside of said notch, the other of said adjacent panels having a rib onits said edge portion nested in said second channel and a rib on itsadjacent edge nested in said first channel on the other side of saidnotch, and means securing saidV panels in the described relationship.

18. A structure as defined in claim 17 wherein the edge surface of saidnotch, on the side thereof corresponding to said one adjacent panel,being parallel to and in abutment with the outer surface of said secondchannel.

References Cited in the le of this patent UNITED STATES PATENTS1,133,072 Vanstrom Mar. 23, 1915 1,358,203 Herrmann et al. Nov. 9, 19201,429,220 Blanton Sept. 19, 1922 2,432,396 Earhart Dec. 9, 19472,644,553 Cushman July 7, 1953. 2,675,040 Raun et al Apr. 13, 1954FOREIGN PATENTS 148,598 Great Britain July 26, 1920

